Make tasks cancellable inside the blink scheduler.

third_party/WebKit/Source/platform/scheduler/base/work_queue_sets_unittest.cc

Index: third_party/WebKit/Source/platform/scheduler/base/work_queue_sets_unittest.cc
diff --git a/third_party/WebKit/Source/platform/scheduler/base/work_queue_sets_unittest.cc b/third_party/WebKit/Source/platform/scheduler/base/work_queue_sets_unittest.cc
index 5b107117250c3069b6fa4339037ba48304c70de7..7dbee0be71c2efafbfa22ba46a1fd9034006deb6 100644
--- a/third_party/WebKit/Source/platform/scheduler/base/work_queue_sets_unittest.cc
+++ b/third_party/WebKit/Source/platform/scheduler/base/work_queue_sets_unittest.cc
@@ -35,7 +35,8 @@ class WorkQueueSetsTest : public testing::Test {
   };
 
   WorkQueue* NewTaskQueue(const char* queue_name) {
-    WorkQueue* queue = new WorkQueue(nullptr, "test");
+    WorkQueue* queue = new WorkQueue(
+        nullptr, "test", TaskQueueImpl::Task::EnqueueOrderComparatorFn);
     work_queues_.push_back(base::WrapUnique(queue));
     work_queue_sets_->AddQueue(queue, TaskQueue::CONTROL_PRIORITY);
     return queue;
@@ -119,8 +120,8 @@ TEST_F(WorkQueueSetsTest, OnPopQueue) {
   WorkQueue* queue2 = NewTaskQueue("queue2");
   WorkQueue* queue3 = NewTaskQueue("queue3");
   queue1->Push(FakeTaskWithEnqueueOrder(6));
-  queue2->Push(FakeTaskWithEnqueueOrder(3));
   queue2->Push(FakeTaskWithEnqueueOrder(1));
+  queue2->Push(FakeTaskWithEnqueueOrder(3));
   queue3->Push(FakeTaskWithEnqueueOrder(4));
   size_t set = 3;
   work_queue_sets_->ChangeSetIndex(queue1, set);
@@ -138,6 +139,58 @@ TEST_F(WorkQueueSetsTest, OnPopQueue) {
   EXPECT_EQ(queue2, selected_work_queue);
 }
 
+TEST_F(WorkQueueSetsTest, OnQueueHeadChanged_RemoveOldestInSet) {
+  WorkQueue* queue1 = NewTaskQueue("queue1");
+  WorkQueue* queue2 = NewTaskQueue("queue2");
+  WorkQueue* queue3 = NewTaskQueue("queue3");
+  queue1->Push(FakeTaskWithEnqueueOrder(6));
+  queue2->Push(FakeTaskWithEnqueueOrder(1));
+  queue3->Push(FakeTaskWithEnqueueOrder(4));
+  size_t set = 3;
+  work_queue_sets_->ChangeSetIndex(queue1, set);
+  work_queue_sets_->ChangeSetIndex(queue2, set);
+  work_queue_sets_->ChangeSetIndex(queue3, set);
+
+  WorkQueue* selected_work_queue;
+  EXPECT_TRUE(work_queue_sets_->GetOldestQueueInSet(set, &selected_work_queue));
+  EXPECT_EQ(queue2, selected_work_queue);
+
+  queue2->PopTaskForTest();
+  work_queue_sets_->OnQueueHeadChanged(queue2, 1);
+
+  EXPECT_TRUE(work_queue_sets_->GetOldestQueueInSet(set, &selected_work_queue));
+  EXPECT_EQ(queue3, selected_work_queue);
+}
+
+TEST_F(WorkQueueSetsTest, OnQueueHeadChanged_RemoveMiddleValueFromSet) {
+  WorkQueue* queue1 = NewTaskQueue("queue1");
+  WorkQueue* queue2 = NewTaskQueue("queue2");
+  WorkQueue* queue3 = NewTaskQueue("queue3");
+  queue1->Push(FakeTaskWithEnqueueOrder(6));
+  queue2->Push(FakeTaskWithEnqueueOrder(1));
+  queue3->Push(FakeTaskWithEnqueueOrder(4));
+  size_t set = 3;
+  work_queue_sets_->ChangeSetIndex(queue1, set);
+  work_queue_sets_->ChangeSetIndex(queue2, set);
+  work_queue_sets_->ChangeSetIndex(queue3, set);
+
+  WorkQueue* selected_work_queue;
+  EXPECT_TRUE(work_queue_sets_->GetOldestQueueInSet(set, &selected_work_queue));
+  EXPECT_EQ(queue2, selected_work_queue);
+
+  queue3->PopTaskForTest();
+  work_queue_sets_->OnQueueHeadChanged(queue3, 4);
+
+  EXPECT_TRUE(work_queue_sets_->GetOldestQueueInSet(set, &selected_work_queue));
+  EXPECT_EQ(queue2, selected_work_queue);
+
+  queue2->PopTaskForTest();
+  work_queue_sets_->OnQueueHeadChanged(queue2, 1);
+
+  EXPECT_TRUE(work_queue_sets_->GetOldestQueueInSet(set, &selected_work_queue));
+  EXPECT_EQ(queue1, selected_work_queue);
+}
+
 TEST_F(WorkQueueSetsTest, OnPopQueue_QueueBecomesEmpty) {
   WorkQueue* queue1 = NewTaskQueue("queue");
   WorkQueue* queue2 = NewTaskQueue("queue");